But such steps may not be enough as Qaddafi forces quickly make inroads in Misurata, ready to kill civilians who want an end to the Libyan leader’s rule. The rebels there are pleading for on-the-ground help from NATO.

But Mr. Obama opposes deploying either US combat forces or the kind of aircraft designed for close-in strikes on urban areas. The administration claims the US has limited resources and little strategic interest in Libya compared with Egypt, Syria, Bahrain, and Yemen.